// Copyright (c) 2016, SolidCP
// SolidCP is distributed under the Creative Commons Share-alike license
// 
// SolidCP is a fork of WebsitePanel:
// Copyright (c) 2015, Outercurve Foundation.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// - Redistributions of source code must  retain  the  above copyright notice, this
//   list of conditions and the following disclaimer.
//
// - Redistributions in binary form  must  reproduce the  above  copyright  notice,
//   this list of conditions  and  the  following  disclaimer in  the documentation
//   and/or other materials provided with the distribution.
//
// - Neither  the  name  of  the  Outercurve Foundation  nor   the   names  of  its
//   contributors may be used to endorse or  promote  products  derived  from  this
//   software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,  BUT  NOT  LIMITED TO, THE IMPLIED
// WARRANTIES  OF  MERCHANTABILITY   AND  FITNESS  FOR  A  PARTICULAR  PURPOSE  ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL,  SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO,  PROCUREMENT  OF  SUBSTITUTE  GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)  HOWEVER  CAUSED AND ON
// ANY  THEORY  OF  LIABILITY,  WHETHER  IN  CONTRACT,  STRICT  LIABILITY,  OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE)  ARISING  IN  ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;
using System.Configuration;
using Microsoft.Win32;

namespace SolidCP.EnterpriseServer
{
	/// <summary>
	/// Summary description for CryptoUtils.
	/// </summary>
	public class CryptoUtils
	{
        static string EnterpriseServerRegistryPath = "SOFTWARE\\SolidCP\\EnterpriseServer";

		public static string CryptoKey
		{
			get 
            {
                string Key = ConfigurationManager.AppSettings["SolidCP.AltCryptoKey"];
                string value = string.Empty;

                if (!string.IsNullOrEmpty(Key))
                {
                    RegistryKey root = Registry.LocalMachine;
                    RegistryKey rk = root.OpenSubKey(EnterpriseServerRegistryPath);
                    if (rk != null)
                    {
                        value = (string)rk.GetValue(Key, null);
                        rk.Close();
                    }
                }

                if (!string.IsNullOrEmpty(value))
                    return value;
                else
                    return ConfigurationManager.AppSettings["SolidCP.CryptoKey"]; 
                
            }
		}

		public static bool EncryptionEnabled
		{
			get
			{
				return (ConfigurationManager.AppSettings["SolidCP.EncryptionEnabled"] != null)
					? Boolean.Parse(ConfigurationManager.AppSettings["SolidCP.EncryptionEnabled"]) : true;
			}
		}

		public static string Encrypt(string InputText)
		{
			string Password = CryptoKey;

			if(!EncryptionEnabled)
				return InputText;

            if (InputText == null)
                return InputText;

			// We are now going to create an instance of the 
			// Rihndael class.
			RijndaelManaged RijndaelCipher = new RijndaelManaged();

			// First we need to turn the input strings into a byte array.
			byte[] PlainText = System.Text.Encoding.Unicode.GetBytes(InputText);


			// We are using salt to make it harder to guess our key
			// using a dictionary attack.
			byte[] Salt = Encoding.ASCII.GetBytes(Password.Length.ToString());

 
			// The (Secret Key) will be generated from the specified 
			// password and salt.
			PasswordDeriveBytes SecretKey = new PasswordDeriveBytes(Password, Salt);

 
			// Create a encryptor from the existing SecretKey bytes.
			// We use 32 bytes for the secret key 
			// (the default Rijndael key length is 256 bit = 32 bytes) and
			// then 16 bytes for the IV (initialization vector),
			// (the default Rijndael IV length is 128 bit = 16 bytes)
			ICryptoTransform Encryptor = RijndaelCipher.CreateEncryptor(SecretKey.GetBytes(32), SecretKey.GetBytes(16));

 
			// Create a MemoryStream that is going to hold the encrypted bytes 
			MemoryStream memoryStream = new MemoryStream(); 

 
			// Create a CryptoStream through which we are going to be processing our data. 
			// CryptoStreamMode.Write means that we are going to be writing data 
			// to the stream and the output will be written in the MemoryStream
			// we have provided. (always use write mode for encryption)
			CryptoStream cryptoStream = new CryptoStream(memoryStream, Encryptor, CryptoStreamMode.Write);

			// Start the encryption process.
			cryptoStream.Write(PlainText, 0, PlainText.Length);


			// Finish encrypting.
			cryptoStream.FlushFinalBlock();

			// Convert our encrypted data from a memoryStream into a byte array.
			byte[] CipherBytes = memoryStream.ToArray();



			// Close both streams.
			memoryStream.Close();
			cryptoStream.Close();

        

			// Convert encrypted data into a base64-encoded string.
			// A common mistake would be to use an Encoding class for that. 
			// It does not work, because not all byte values can be
			// represented by characters. We are going to be using Base64 encoding
			// That is designed exactly for what we are trying to do. 
			string EncryptedData = Convert.ToBase64String(CipherBytes);

 

			// Return encrypted string.
			return EncryptedData;
		}


		public static string Decrypt(string InputText)
		{
			try
			{
				if(!EncryptionEnabled)
					return InputText;

                if (InputText == null || InputText == "")
                    return InputText;

				string Password = CryptoKey;
				RijndaelManaged  RijndaelCipher = new RijndaelManaged();

 
				byte[] EncryptedData = Convert.FromBase64String(InputText);
				byte[] Salt = Encoding.ASCII.GetBytes(Password.Length.ToString());


				PasswordDeriveBytes SecretKey = new PasswordDeriveBytes(Password, Salt);

				// Create a decryptor from the existing SecretKey bytes.
				ICryptoTransform Decryptor = RijndaelCipher.CreateDecryptor(SecretKey.GetBytes(32), SecretKey.GetBytes(16));
 

				MemoryStream  memoryStream = new MemoryStream(EncryptedData);

				// Create a CryptoStream. (always use Read mode for decryption).
				CryptoStream  cryptoStream = new CryptoStream(memoryStream, Decryptor, CryptoStreamMode.Read);


				// Since at this point we don't know what the size of decrypted data
				// will be, allocate the buffer long enough to hold EncryptedData;
				// DecryptedData is never longer than EncryptedData.
				byte[] PlainText = new byte[EncryptedData.Length];

				// Start decrypting.
				int DecryptedCount = cryptoStream.Read(PlainText, 0, PlainText.Length);


				memoryStream.Close();
				cryptoStream.Close();

				// Convert decrypted data into a string. 
				string DecryptedData = Encoding.Unicode.GetString(PlainText, 0, DecryptedCount);


				// Return decrypted string.   
				return DecryptedData;
			}
			catch
			{
				return "";
			}
		}

        public static string SHA1(string plainText)
        {
            // Convert plain text into a byte array.
            byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

            HashAlgorithm hash = new SHA1Managed();;

            // Compute hash value of our plain text with appended salt.
            byte[] hashBytes = hash.ComputeHash(plainTextBytes);

            // Return the result.
            return Convert.ToBase64String(hashBytes);
        }
	}
}
